Question

The algebraic sum of the deviation of 20 observations from 30 is 2.Therefor, what is the mean of this observatio?

Answer 1

Explanation:

Let the 20 deviations be a

1

,a

2

,...,a

20

Therefore the observations are (30+a

1

),(30+a

2

),...,(30+a

20

)

Given that sum of the deviations is 2

Therefore, a

1

+a

2

+...+a

20

=2 ------(1)

Hence, mean=

20

(30+a

1

)+(30+a

2

)+...+(30+a

20

)

⟹mean=

20

a

1

+a

2

+...+a

20

+20(30)

⟹mean=

20

2+20(30)

(from (1))

⟹mean=

20

602

=30.1

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